Encapsulated liquid crystal apparatus having low off-axis haze, operable by a sine-wave power source and including a dye

Abstract

A liquid crystal apparatus including a low birefringence encapsulated liquid crystal material in a containment medium. The liquid crystal material contains a dye that conforms to the structure of the liquid crystal material. The difference between the ordinary index of refraction and extraordinary index of refraction of the liquid crystal material is between about 0.050 and 0.115. The index of refraction of the containment is greater than the ordinary index of refraction of the liquid crystal material. The liquid crystal apparatus provides low haze at off-axis viewing angles, permits efficient sine-wave power operation, and provides energy control.

What is claimed is: 
     
       1. A liquid crystal apparatus comprising: an encapsulated liquid crystal material in a containment medium, said liquid crystal material containing a dye that conforms to the structure of the liquid crystal material, and having an extraordinary index of refraction and an ordinary index of refraction wherein the difference between said extraordinary index of refraction and said ordinary index of refraction is between about 0.050 and 0.115, and wherein the containment medium has an index of refraction greater than said ordinary index of refraction. 
     
     
       2. The liquid crystal apparatus of claim 1 disposed between two optically transparent panels to control transmission of light therethrough. 
     
     
       3. The liquid crystal apparatus of claim 2 further including a sine-wave power source for applying an electric field across said liquid crystal material to transmit light. 
     
     
       4. The liquid crystal apparatus of claim 1 wherein the difference between said extraordinary index of refraction and said ordinary index of refraction is between about 0.080 and 0.100. 
     
     
       5. The liquid crystal apparatus of claim 1 wherein the difference between the index of refraction of the containment medium and said ordinary index of refraction is not greater than about 0.020. 
     
     
       6. The liquid crystal apparatus of claim 1 further including two optically transparent panels between which the liquid crystal apparatus is disposed to form a window means wherein the liquid crystal apparatus controls transmission of light through said window means. 
     
     
       7. The liquid crystal apparatus of claim 1 wherein said dye is a pleochroic or dichroic dye. 
     
     
       8. The liquid crystal apparatus of claim 1 further including electrode means for applying an electric field across at least some of said liquid crystal material, electrical circuit means for providing electrical power to said electrode means, and said electrical circuit means including a sine-wave power source for applying said electric field without producing objectionable haze. 
     
     
       9. A window comprising two optically transparent panels between which is disposed an encapsulated liquid crystal material in a containment medium, said liquid crystal material containing a dye that conforms to the structure of said liquid crystal material, and having an extraordinary index of refraction and an ordinary index of refraction wherein the difference between said extraordinary index of refraction and said ordinary index of refraction is between about 0.050 and 0.115, and wherein the containment medium has an index of refraction greater than said ordinary index of refraction, and wherein said liquid crystal material is switchable between a field-on and field-off state by an application of an electric field from a sine-wave power source without producing objectionable haze levels. 
     
     
       10. The liquid crystal apparatus of claim 9 wherein the difference between the index of refraction of the containment medium and the ordinary index of refraction of said liquid crystal material is between about 0.010 and 0.20.